Generally, controllers are used to adjust a control variable (may also be referred to as controlled variable, process variable, actual value, measured value) to a reference variable (set point, set value). Depending on the parameter to be controlled (e.g., temperature, pressure, voltage, charge or in general any physical parameter) and the system to be controlled (room, fluid tank, etc.), a more or less complex structure of the regulator may be necessary. A controller typically has to consider system dynamics in order to reliably adjust the control variable to the reference variable and within a reasonable time.
In the field of control engineering, for example, so-called PID controllers (proportional-integral-derivative controllers) are known. A PID controller requires detailed knowledge of the behavior of the system/parameter to be controlled. The coefficients for the PID controller will be set according to this behavior. If the dynamics of the controlled system change, it may be necessary to change the coefficients of the PID controller.